Cross-Layer MAC Enabling Virtual Link for Multi-Hop Routing in Wireless Ad Hoc Networks

Efficient routing is a fundamental issue in multi-hop wireless ad hoc networks. In this paper, we study the limitation of traditional routing structure in multi-hop wireless ad hoc networks due to (a) the layered structure of a wireless protocol stack and (b) the lack of coordination between medium access control (MAC) and routing protocols. These limitations result in long processing delays in a relay/forwarding node. In order to alleviate these issues, we propose a solution based on cross-layer MAC design, which improves the coordination between MAC and routing layers using an idea we call ``virtual link". The virtual link idea was implemented and tested in an ad hoc wireless network testbed. Experimental results show that the proposed cross-layer design significantly improves the performance in terms of reduced round trip time (RTT), reduced processing time in the intermediate relay/forwarding nodes and increased throughput compared to a legacy architecture.